Multiple Studies Link Everyday Lawn Products To Canine Cancer

With summer in full swing, the generally higher temperatures often mean pets will be spending more time outdoors, but it also means that dog owners must be vigilant of the dangers of lawn chemical, as numerous studies over the past few years have shown strong connections between herbicides and lawn chemicals using 2,4-D, and canine cancers.

The World Health Organization's International Agency for Research on Cancer classified 2,4-D as “possibly carcinogenic to humans.”

The classification of the weed killer, 2,4-dichlorophenoxyacetic acid, known as 2,4-D, was made by the WHO's International Agency for Research on Cancer (IARC).

The IARC said it reviewed the latest scientific literature and decided to classify 2,4-D as “possibly carcinogenic to humans.”

Recent studies have found that lawn chemicals travel to untreated neighboring yards, and inside homes, with chemicals even being found in the urine of dogs whose owners had never chemically treated their lawns. A six-year study, by the Tufts University School of Veterinary Medicine, linked lawn pesticides to canine malignant lymphoma (CML), finding “specifically, the use of professionally applied pesticides was associated with a significant 70% higher risk of CML. Risk was also higher in those reporting use of self-applied insect growth regulators,” based on questionnaire results from dog owners participating in the study.

In a separate study, using a similar methodology, it was found that herbicides also contribute to canine malignant lymphoma. The researchers discovered that herbicides containing 2,4-D doubled the risk of CML when dog owners used it four or more times per year.

“Chemicals were detected in the urine of dogs in 14 of 25 households before lawn treatment, in 19 of 25 households after lawn treatment, and in 4 of 8 untreated households. Chemicals were commonly detected in grass residues from treated lawns, and from untreated lawns suggesting chemical drift from nearby treated areas,” a 2013 study found.

The researchers concluded that 2,4-D herbicides and other lawn chemicals cause a “significantly higher” risk of canine bladder cancer. Additionally, specific breeds, including Beagles, Scottish Terriers, Shetland Sheepdogs, West Highland White Terriers, and Wire Hair Fox Terriers have an increased susceptibility due to a genetic predisposition to bladder cancer.

Potentially toxic chemical exposure can result from ingestion, inhalation, or simple contact with skin.

Revealing the potential danger to humans, another study found contaminants of the herbicide 2,4-D inside and throughout homes both prior to and after outdoor application, highlighting just how readily pets absorb and track lawn chemicals from their intended targets into homes.

The study concluded, “removal of shoes at the door and the activity level of the children and pets were the most significant factors affecting residue levels indoors after application.”

This research, as a whole, is critically important, not only for the health of pets, but for their human owners as well, as Non-Hodgkin's lymphoma has a very similar histology and epidemiology as CML, and has also been linked to 2, 4-D exposure.